The present invention relates generally to patch antennas, and more particularly to the utilization of a pin fin ground plane structure for a linearly-polarized patch antenna.
Patch antennas are planar antennas used in wireless links and other microwave applications. A conventional linearly-polarized, single-band patch antenna consists of a dielectric substrate with a ground plane on the back-side of the dielectric substrate. On the front-side of the dielectric substrate is a square or rectangular conductive area also known as a “patch”, which gives patch antenna its name. Typically a coaxial cable acts as a feed line to and from the “patch” for transmitting or receiving signals. In addition, the length of the patch in the direction of the feed is typically slightly less than half a wavelength of the operating frequency.
The ease of patch antenna fabrication on a flat substrate is a main selling point of the patch antenna. Though patch antennas have low gain as compared to large dish/parabolic type antennas, they can be arranged in an array to achieve higher gains. A commercial patch antenna, when opened up, typically involves an array of different shaped patches. For linearly-polarized radiation, the simplest patch element is a rectangle.
However, there are certain deficiencies with respect to a conventional patch antenna design. The resonant length of a conventional patch antenna is directly proportional to the intrinsic speed of light in the dielectric substrate over a flat ground plane, which is typically a published value for the substrate material. The radiating structure is a half wave resonating structure. An electric field exists between the patch and the ground plane. Since the field is not fully enclosed near its edges, fringing fields, which in turn is a source of radiation, are generated. Other factors also influence the resonant frequency of the patch antenna. These factors include: ground plane size, dielectric substrate thickness, metal (copper) thickness, and patch width (impedance). The width of the patch is chosen to provide a suitable radiation resistance and operational bandwidth.
Desirable in the art of linearly-polarized microstrip patch antenna, are improved patch antenna designs that provide for smaller size, lower weight, and decreased fabrication and assembly costs while maintaining conventional patch antenna performance.